For diverse technological purposes it is necessary to form surface layers on metals to insure a firm and durable adhesive contact with other materials, and with organic materials in particular. Typical examples are phosphate, chromate, and oxide layers used to bind paints, plastics, insulating foams, rubber, and other organic coatings to iron, aluminum, zinc, and their alloys.
The production of surface layers is achieved by reaction of the metal with a specially composed media at controlled conditions. The resulting layer is either crystalline, as in phosphate or oxide layers, or it is partly crystalline and partly amorphous in structure, as in chromate layers.
The industrial manufacture of these surface layers requires complicated multistep procedures, large processing plants, and a very large investment in power and equipment. Expensive water-neutralization and waste-purification procedures and equipment are also needed whenever the coating solution contains hazardous compounds, such as chromates.
The treatment of metals with a coating is dislosed in Fisher, U.S. Pat. No. 3,297,616; Mohr, U.S. Pat. No. 4,404,114; and Vashi, U.S. Pat. No. 4,497,667. These references are distinguishable from the invention, because unlike the present composition and process they are concerned with a pretreatment process for activation of another adhesive (Vashi); a pigmented and self curing final coating (Fisher); and a corrosion inhibitor (Mohr).
These disadvantages are largely alleviated by the present invention, which provides a novel composition for the production of layers with a high specific surface on iron, aluminum, zinc, and their technical alloys.